Morphology of anatase crystals and their aggregates synthesized hydrothermally from aqueous mixtures of titanium alkoxide and different alkylammonium hydroxides(<Feature>Aqueous Solution Science for Ceramic Processing II)

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Anatase was hydrothermally synthesized from transparent aqueous sols including layered titanate colloids. The reaction sols were prepared from titanium isopropoxide and different alkylammonium hydroxides (NR_4OH). The influence of the type of NR_4OH on the morphology of the anatase crystals and their aggregates was examined. We previously reported that although anatase has a tetragonal lattice, six-pointed starlike anatase aggregates were synthesized from the sols prepared using N(CH_3)_4OH. With increasing the alkyl chain length of NR_4OH, the number of the starlike aggregates decreased, and their arms became thicker and shorter. When N(C_4H_9)_4OH was used, needlelike anatase crystals elongated along the c-axis were formed rather than starlike aggregates. The use of NR_4OH with long alkyl chains were expected to retard stacking of the layered titanate during hydrothermal synthesis. The stacking and exfoliation of the layered titanate colloids may play an important role in the morphology of the resulting anatase crystals and their aggregates.
社団法人日本セラミックス協会の論文
2009-03-01